Boundary-anchored thalamic ADC profiling shows spatially structured abnormalities in multiple sclerosis.

PURPOSE: Diffusion MRI is sensitive to tissue abnormalities in multiple sclerosis (MS), but conventional region-of-interest measures reduce spatially structured signal patterns to a single summary value. We evaluated boundary-anchored thalamic apparent diffusion coefficient (ADC) profiling in MS using line-based edge-anchored profiling (LEAP). MATERIALS AND METHODS: In this retrospective matched-control study, age- and sex-matched controls (CTRL, n = 28) and participants with relapsing-remitting MS (RRMS, n = 14) or secondary progressive MS (SPMS, n = 14) were analyzed on the same 3T MRI scanner using the same diffusion protocol. LEAP was applied bilaterally at the medial thalamic surface adjacent to the third ventricle. Participant-averaged bilateral summary metrics and exploratory side-specific profile-shape metrics were derived from ADC curves. RESULTS: The clearest signal was observed in comparisons between MS and matched controls, with the largest number of differences seen for SPMS versus controls. Compared with controls, SPMS showed a higher ventricle-near mean ADC (p = 0.004), higher profile maximum ADC (p = 0.003), and a steeper early profile slope (p = 0.005). RRMS generally showed intermediate values. Direct RRMS-versus-SPMS comparisons of bilateral summary metrics were limited. Exploratory right-sided profile-shape metrics and left-right asymmetry measures suggested possible phenotype-related differences. CONCLUSION: Boundary-anchored thalamic ADC profiling detected spatially structured abnormalities in MS relative to matched controls, with the strongest deviation in SPMS. Exploratory shape-based findings should be considered hypothesis-generating and suggest additional profile-level information beyond bilateral summary values. KEY POINTS: · LEAP enables spatially resolved thalamic ADC assessment.. · SPMS showed strongest deviations from matched controls.. · RRMS demonstrated intermediate profile characteristics.. · Profile morphology contained information beyond bilateral averages.. · Boundary-anchored profiling complements conventional ROI analysis.. CITATION FORMAT: · Garner M, Fries F, Garner C et al. Boundary-anchored thalamic ADC profiling shows spatially structured abnormalities in multiple sclerosis. Rofo 2026; DOI 10.1055/a-2941-6690.